Microfluidic Channel Sealing With Directionally Grown Trench Plugs
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Solution Overview
Problem
Current microfluidic channel structures and fabrication methods are inadequate for efficient formation and integration into semiconductor devices, particularly in terms of alignment with crystallographic planes and effective obstruction of trench entrances.
Innovation Solution
A trench is formed in a semiconductor substrate with a semiconductor layer having a thicker portion to obstruct the entrance, creating a cavity that defines a microfluidic channel, which is aligned with crystallographic planes and formed using epitaxial growth and selective etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trench is formed in a semiconductor substrate to create a microfluidic channel, then the microfluidic channel can be integrated into the semiconductor device, but the trench entrance needs to be effectively obstructed to define the channel boundaries
Solution Approach 1:
The semiconductor layer is segmented into two distinct portions: a first portion that lines the trench sidewalls to define the channel, and a second portion that forms a thicker plug to obstruct the trench entrance. This segmentation allows each portion to perform its specific function effectively while maintaining overall structural simplicity.
Solution Approach 2:
The semiconductor layer exhibits local quality variation with different thicknesses in different regions. The first portion has a thinner profile suitable for lining the trench, while the second portion has a thicker profile for effective obstruction. This local differentiation resolves the contradiction by providing the right structure in the right location.
2Manufacturing precision
If the semiconductor layer is grown to obstruct the trench entrance, then the microfluidic channel boundaries are defined, but the growth process must be precisely controlled to achieve the required thickness variation
Solution Approach 1:
The epitaxial growth process is designed with preliminary actions that set the stage for subsequent thickness variation. By controlling the initial growth conditions and introducing variations during the growth process, the desired thickness profile is achieved systematically rather than requiring complex post-processing adjustments.
Solution Approach 2:
The epitaxial growth process utilizes parameter changes during the growth sequence to achieve the required thickness variation. By modifying growth parameters such as temperature, pressure, or gas flow rates at different stages, the semiconductor layer transitions from a uniform thin layer to a structured layer with a thicker obstruction portion, balancing precision with manufacturability.
3Stability of the object's composition
If the microfluidic channel is aligned with crystallographic planes, then the channel structure benefits from inherent material properties, but the alignment requires precise orientation control during fabrication
Solution Approach 1:
The trench and resulting microfluidic channel are designed with asymmetric orientation relative to the semiconductor substrate's crystallographic planes. By deliberately aligning the trench at a specific angle (e.g., <110> direction in silicon), the structure exploits the anisotropic properties of the crystal lattice to achieve stable, well-defined channel boundaries while the asymmetric design simplifies the alignment process compared to requiring perfect symmetry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the formation of microfluidic channels by aligning them with crystallographic planes and obstructing the trench entrance, enhancing the integration of microfluidic systems into semiconductor devices.
Implementation Method 1
formed using epitaxial growth and selective etching processes
Implementation Method 2
directionally-grown plugs
Data Source
AI summary
Structures for a microfluidic channel and methods of forming a structure for a microfluidic channel. The structure comprises a trench in a semiconductor substrate and a semiconductor layer inside the trench. The trench has an entrance and a sidewall extending from the entrance into the semiconductor substrate. The semiconductor layer has a first portion surrounding a portion of the trench to define a cavity and a second portion positioned to obstruct the entrance to the trench. The second portion of the semiconductor layer is thicker than the first portion of the semiconductor layer.